NASA operated two converted 747s to transport the space shuttle. Boeing 747-100, N905NA started life in September 1970 with American Airlines as N9668. In July 1974 it was sold to NASA were it remains in service today. Boeing 747-100, N911NA was sold to Japan Airlines in September 1973 as JA8117. It was back with Boeing registered as N747BL in April 1988. In October it was sold to NASA and numbered N911NA.